Apparatus for forming nitrogen oxides



UNi'iED STATES PATENT GFFEQE APPARATUS FOR FORMING NITROGEN OXIDES Fredrik W. de Jahn, New York, N. Y., assignor to Frank A. Bower, Bayside, N. Y.

Application April 25, 1928, Serial No. 272,618 Renewed December 29, 1932 4 Claims. (01. 23288) This invention relates to the manufacture of For this purpose the end of the shell it is prooxides of nitrogen, and more particularly to the vided with a header i5 and diaphragm i6 conmanufacture of nitric acid by oxidizing of amnected to pipes adapted to carry air or other gas monia gas. v into the oxidizing space and close to the gauze 5 The oxidation of ammonia takes place at high 9. The diaphragm 96 has set into it a system =15 temperatures and involves a large amount of heat, of U-shaped pipes 29, each pipe extending from and I have found that it is advantageous to lower the upper portion of the diaphragm to a downthe temperature of the gases as soon as possible Ward bend positioned adjacent the gauze 9 and after oxidation. then back to an opening in the lower portion of 10 The object of my invention is to provide a simple the diaphragm. The header i5 is provided with 10' and durable apparatus for the oxidation of the an entrance port space 2i and a discharge port ammonia and the immediate reduction of its temspace 22 separated by an intermediate baffle 23 perature. so that air entering through piping 2t will pass Further objects of the invention in the structhrough the U-pipes 2t and then out through tural details of the apparatus and its use to preport 22 and piping I to the mixing nozzle 6, the 15 heat the air for the oxidizing will appear from the U-shaped pipes being of varying lengths of corfollowing description taken in connection with the responding inside diameters so as to present the accompanying drawing, in which same resistance to the flow of the gases, this in Fig. 1 is a diagrammatic elevational view of the order that the flow of gases may be uniform 0 apparatus. through all the pipes. In this way the cooling Fig. 2 is a partial vertical sectional view of the of the hot gases from the gauze 9 is used to preoxidizing chamber. heat the air or other gas used for the oxidizing Fig. 3 is a. vertical cross sectional View on the process. line 3-3 of Fig. 2, and The material used for the shell and other por- 25 Fig. 4 is an enlarged sectional view of a portion tions of the structure is preferably chromium of Fig. 2. 1 alloy such as asco1ay,-the shell parts being pref- In the apparatus illustrated in the drawing the erably of sheet material, as indicated, with welded ammonia gas is supplied through the pipe 5 to the joints to the surrounding ring flanges. mixing nozzle 6, receiving its supply of air through The bracket l2 carrying the gauze ii is a the pipe I and passing it in jet form into the separable gauze unit insertable within the shell 39 right-hand end of the oxidizing chamber desig- It insulated therefrom by the lining H. The

Ila-ted g ne y at 3 and against the Platinum gauze 9 is placed between the rings 25, 2% carried gauze 9 f m a diaph agm acros tne chamby the bracket l2. The rings 25, 26 with the her adjacent its entrance end. The oxidation takgauze 9 t r t are d together in 8 Place in the neighborhood of the au e 9 d assembled relation and cIamped to the extension 35 v V610DS l rge amount of. heat and therefore the 21 of the bracket l2 by means of clamping bolts generally cylindrical shell it is lined its full length 28 passing through the rings and threaded into with a material ll of high insulating characteristh extension 21. The ring 25 is provided with ties, Such as 81100611- At the right hand end of e diametrically opposite elongated apertures 2.! for shell Ill the l n g H is thinned Out to DP the spaced silica rods 39 which form a brace for 40 mately thickness for the reception Of a the gauze 9 in the direction pposite to the enter.. flanged bracket i2 which extends inwardly within m jet from the nozzle 3 preventing any bulging the shell forming a removable supporting strucof the gauze toward the pipes 211 ture for the gauze 9. The oxidizing chamber 8 be- The gauze unit is held in position within t tw e e gauze 9 and its/Fight hand end i lined shell I0 between end flange ring 3! secured to the W a teftactory materlat therejtn and outer end of the shell and the outer flange of the fittfad Wlthm the bracket m Sect-110ml r.mgS end header 32 by means of clamping bolts 33 wh ch are preferably of dust prooI material sue which pass through the end flange ring 3| the as isolantite so as to avoid clogging of the platb 2 h t Th hot ases from the gauze 9 racket flange 34 of the bracket l and t e on er 9 mum gauze e g ii i the header 32 suitable gaskets b8111 pass outward through the opening M to the nitric ange 0 h acid absorption apparatus and the main Object mserted therebetween. The gauze unit may t us of this invention is to provide for til; loweritngftfiif be fifg tie ilee g ggfg 2 21110 grt ilagiiiansggllpilrsl g erature of these ases in e mos e separa l g i e nt r r nner. g and this also gives complete access to the entire 55 interior of the oxidizing chamber. The header plate I5 and its diaphragm or tube sheet I6 are also removably attached by bolts 35 to the end flange ring 36 so that the whole shell construction can be readily dismantled from either end. If desired, baflie partitions may be inserted between the gauze 9 and the outlet l4, these baflles being provided with tube openings leaving an annular orifice around the cooling tubes through which the hot gases are forced into close contact with the cooling tubes. This construction may be used at atmospheric pressure, and is particularly advantageous when working with higher pressure.

The header is also provided with an enlarged section 37 having an opening over Which is an observation cover 39 in which is placed an observation window 38 clamped to the enlarged section by means of clamping bolts 40. This window is so situated that the entire gauze 9 can be observed to see that it is functioning properly.

In starting the operation and to properly ignite the gases an igniting system is inserted through the header 32 consisting of a hydrogen or other gas inlet tube 4! and an electric terminal 42 terminating within the chamber 8. One side of the electric circuit is grounded on the apparatus and the other side connected to the terminal 42 so that a spark from the terminal 42 jumps across the spark gap 43 between the end of the terminal 42 and the end of the tube 4 I.

In the apparatus of this invention the hot freshly formed oxides are immediately cooled so as to avoid the effect of hot temperature in breaking down the compounds formed by the burning. This maintains or increases the final yield of the desired oxides. At the same time the rapid cooling minimizes the high temperature efiects and avoids the complications necessary in handling these very hot gases which burn at a temperature of about 900 C. and are quickly cooled in the apparatus of this invention to a temperature in the neighborhood of 550 to 600 C. by the gases forced at a rapid rate through the tubes 28. The U-shaped cooling tubes are free to expand and contract under the temperature changes without imposing any strains upon the shell or other parts, and at the same time within the relatively small shell space they afiord a very large and efiicient cooling area. The structure of this invention thus provides a very simple efficient and porting bracket for said gauze having a section extending within said shell, heat insulating means for insulating said section and its point of attachment to said gauze from said shell and from said combining chamber.

2. In apparatus for forming nitrogen oxides the combination with an inlet for ammonia gas and an inlet for an oxidizing gas of combining means therefor comprising a metal gauze unit adapted to form nitrogen oxides of high temperature, a n

shell forming a combining chamber and cooling tubes supported at one end of said shell in close proximity to said gauze to cool said oxides upon their formation, said gauze unit extending into said shell and detachably supported to the opposite end portion of said shell.

3. In apparatus for forming nitrogen oxides the combination with an inlet for ammonia gas and an inlet for an oxidizing gas of combining means therefor comprising a metal gauze within said shell, a supporting bracket for said gauze one end of which is attached to said gauze and the opposite end of said bracket tothe end of said shell at its exterior, igniting means within said combining chamber, means for observing said .gauze from the exterior of said shell and cooling means within said shell to cool said oxides immediately upon their formation.

4. In apparatus for forming nitrogen oxides the combination with an inlet for ammonia gas and an inlet for an oxidizing gas of combining means therefor comprising a shell forming a combining chamber, a metal gauze unit attached to one end of said shell and extending therein adapted to form nitrogen oxides of high'temperature, insulating means extending the entire length of the interior of said shell having a cutaway section at one end in which said gauze unit is located and insulating means within the interior of said gauze unit.

FREDRIK W. DE JAHN. 

